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Esperanzaite

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La Esperanza Mine, Durango, Mexico
© 2004 JBS

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Formula:
NaCa
 
2
Al
 
2
(AsO
 
4
)
 
2
(OH)F
 
4
 · 2H
 
2
O
System:MonoclinicColour:Pale blue-green
Lustre:VitreousHardness:4½
Name:Named after the discovery locality, the La Esperanza Mine, Durango, Mexico.
This page provides mineralogical data about Esperanzaite.

Classification of Esperanzaite

IMA status:Approved 1998
Strunz 8th edition ID:7/D.25-38
Nickel-Strunz 10th (pending) edition ID:8.DM.05

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
M : With large and medium-sized cations, (OH, etc.):RO4 > 2:1
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Type Occurrence of Esperanzaite

Type Locality:La Esperanza Mine, Durango, Mexico
Year of Discovery:1999
Geological Setting of type material:Found on an altered rhyolite.

Physical Properties of Esperanzaite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Pale blue-green
Hardness (Mohs):4½
Tenacity:Brittle
Cleavage:Perfect
parallel to c
Fracture:None observed
Density (measured):3.24 g/cm3
Density (calculated):3.36 g/cm3

Crystallography of Esperanzaite

Crystal System:Monoclinic
Cell Parameters:a = 9.687Å, b = 10.7379Å, c = 5.5523Å
β = 105.32°
Ratio:a:b:c = 0.902 : 1 : 0.517
Unit Cell Volume:V 557.02 ų (Calculated from Unit Cell)
Z:2
Morphology:Botryoidal patches to 0.8 cm across and radiating crystals in spheres to 1.5 mm in diameter.
X-Ray Powder Diffraction:
d-spacingIntensity
5.364(80)
4.796(80)
3.801(80)
3.527(90)
2.966(100)
2.700(90)

Optical Data of Esperanzaite

Type:Biaxial (-)
RI values: nα = 1.580 nβ = 1.588 nγ = 1.593
2V:Measured: 74° , Calculated: 76°
Maximum Birefringence:δ = 0.013

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r < v moderate
Pleochroism:Non-pleochroic

Chemical Properties of Esperanzaite

Formula:
NaCa
 
2
Al
 
2
(AsO
 
4
)
 
2
(OH)F
 
4
 · 2H
 
2
O
Essential elements:Al, As, Ca, F, H, Na, O
All elements listed in formula:Al, As, Ca, F, H, Na, O
Analytical Data:
As (26.50)
Al (10.16)
Ca (14.83)
Zn (0.70)
Na (2.86)
F (13.9)
H2O (8.65) by Karl-Fischer titration
O (24.45) calculated
Empirical Formula:
Na
 
0.68
Ca
 
2.03
Al
 
2..06
(AsO
 
4
)[(As
 
0.94
Zn
 
0.07
)O
 
3.87
]F
 
4.00
(OH) · 2.13H
 
2
O

Relationship of Esperanzaite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
8.DM.05Morinite
Na
 
2
Ca
 
4
Al
 
4
(PO
 
4
)
 
4
(F,OH)
 
10
 · 3H
 
2
O
8.DM.10Clinotyrolite
Ca
 
2
Cu
 
9
(AsO
 
4
,SO
 
4
)
 
4
(OH,O)
 
10
 · 10H
 
2
O
8.DM.10Tyrolite
Ca
 
2
Cu
 
9
(AsO
 
4
)
 
4
(CO
 
3
)(OH)
 
4
 · 11-12H
 
2
O
8.DM.15Betpakdalite
{Mg(H
 
2
O)
 
6
}Ca
 
2
(H
 
2
O)
 
13
[Mo
6+
8
As
5+
2
Fe
3+
3
O
 
36
(OH)](H
 
2
O)
 
4
8.DM.15Melkovite
CaFe
3+
2
Mo
 
5
(PO
 
4
)
 
2
O
 
10
(OH)
 
12
 · 8H
 
2
O
8.DM.15Natrobetpakdalite
(Na
 
2
,Ca)Fe
 
2
(As
 
2
Mo
 
6
O
 
28
) · 15H
 
2
O
8.DM.20Phosphovanadylite
(Ba,Ca,K,Na)x[(V,Al)4P2(O,OH)16]·12(H2O) x~0.66
8.DM.25Yukonite
Ca
 
3
Fe
3+
 
(AsO
 
4
)
 
2
(OH)
 
3
 · 5H
 
2
O
8.DM.30Uduminelite
Ca
 
3
Al
 
8
(PO
 
4
)
 
2
O
 
12
 · 2H
 
2
O
8.DM.35Delvauxite
CaFe
 
4
(PO
 
4
,SO
 
4
)
 
2
(OH)
 
8
 · 4-6H
 
2
O not confirmed ·
8.DM.40Santafeite
(Na,Ca,Sr)
 
12
(Mn
2+
 
,Fe
3+
 
,Al,Mg)
 
8
Mn
4+
8
(VO
 
4
)
 
16
(OH,O)
 
20
 · 8H
 
2
O

Other Names for Esperanzaite

Synonyms:
IMA1998-025
Other Languages:
German:Esperanzait
Russian:Эсперансаит
Spanish:Esperanzaita

Other Information

Fluorescence in UV light:not fluorescent
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Esperanzaite

Reference List:

- +
Foord, E.E., Hughes, J.M., Cureton, F.F. II, Maxwell, C.H., Falster, A.U., Sommer, A.J., Hlava, P.F. (1999): Esperanzaite, NaCa2Al2(As5+O4)2F4(OH)•2H2O, a new mineral species from the La Esperanza mine, Mexico: descriptive mineralogy and atomic arrangement. Canadian Mineralogist 37, 67-72

Internet Links for Esperanzaite

Search Engines:
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    • External Links:
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  • Look for Esperanzaite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Esperanzaite details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
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  • Search for - Esperanzaite - on e-Rocks Mineral Sales & Auctions
  • Rare and Unusual minerals at Mineralogical Research Company
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    • Localities for Esperanzaite

    Hide Locality List
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Mexico
     
    • Durango
    		[Can. Mineral. (1999) 37, 67.; AmMin 85:263]
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